The Bandz are now contraband. Schools in several states, including New York, Texas, Florida and Massachusetts, have blacklisted Silly Bandz, those stretchy, colorful bracelets that are creeping up the forearms of school kids across the U.S. And starting this week, all 800-some kids at my son’s elementary school in Raleigh, N.C., were commanded to leave at home their collections of rubber band–like bracelets, which retail for about $5 per pack of 24. What could possibly be so insidious about a cheap silicone bracelet?